POST MORTEM CHANGES Mbchb year 4 Final.pptx

Helps the students in the understanding of forensic medicine, what happens after death

1. Post mortem changes Dr. Ali Waiswa

2. Changes After Death Early Post-Mortem Changes Skin changes Eye changes Post-mortem staining/hypostasis/ lividity Cadaveric changes in muscle: - Primary relaxation Rigor mortis Secondary relaxation Cooling of the body 2

3. Changes in Skin Loss of elasticity Pale and ash-white colour Tattoo marks not affected Ante-mortem wounds not affected Changes in the Eyes Loss of reflexes (corneal and pupillary) Corneal opacity and clouding (2 hours). Taches noires sclerotiques (3 hours).

4. Normal eye Dilated pupil tache noire

5. Post-Mortem Staining (Hypostasis)/ Livor mortis Reddish purple or bluish discoloration of skin and organs due to accumulation of blood in toneless capillaries and small veins in dependent parts due to gravity . It is the purple-red discoloration that results from settling of blood to the dependent portions of the body Mottled patches appear ½ to 1 hour Patches gradually increase in size and fuse in about 3 hours Fully developed (6-12 hours) and relatively fixed (6-8 hours ) Absent in areas of contact flattening . Blood is pushed out of the areas of the body that are lying on the ground or on other objects, resulting in patches of contact pallor

6. Once livor is fully developed, it becomes fixed and will no longer blanche with pressure If the body is moved between the time of visible livor and fixed livor, two different patterns of livor and contact pallor may develop. Different patterns of livor in the same body are proof that the body has been moved

7. Factors affecting development of post mortem lividity Heat , sepsis , heart failure may accelerate fixation of lividity Fixation of lividity is delayed by internal /external hemorrhage and cold

8. POST MORTEM HYPOSTASIS

9. As livor mortis develops, if the position of the body is changed the pattern of lividity may change as happened in the body shown

10. Medico-Legal Importance of Post-Mortem Staining Position of body – change in position Time since death ( staining is fixed or not) Its distribution may suggest manner of death Inappropriate lividity patterns or locations may suggest a body has been moved after death Colour of PM staining may suggest cause of death Carbon monoxide poisoning( Cherry Red). Cyanide poisoning (Brick Red). Exposure to cold (Cherry red).

11. Cooling of the Body (Algor Mortis) Body loses heat until it reaches temperature of its surroundings. Temperature recorded by inserting a chemical thermometer (25cm long) into rectum or under liver for 2-3 minutes. Estimation of time of death from cooling of the body Body temperature reaches atmospheric temperature in about 12-18 hours. 12

12. Estimation of time since death from cooling of the body Moritz’s formula ( 98.6 ˚ F- rectal temp) divided by 1.5 hrs = hours since death Alternate formula:-- a body cools at 1.5˚F/hour for first 12 hours after death , then 1˚F/hour for next 12-18 hours. 13

13. Factors Modifying Cooling of Body Difference in temperature between body and surrounding Build/Physique of cadaver Environmental temperature of body Temperature of body at the time of death and Post-mortem caloricity Amount of clothing /bedding 14

14. Post-mortem Caloricity Temperature rise observed for the first two hours or so in bodies after death from: - Excessive bacterial activity Regulation of heat production disturbed before death Great increase in heat production in muscles before death. 15

15. Rigor mortis The lack of oxygen means that energy cannot be obtained from glycogen via glucose using oxidative phosphorylation and so adenosine triphosphate (ATP) production from this process ceases and the secondary anoxic process takes over for a short time This leads to lactic acid production making the cells more acidic The low ATP and high acidity makes the actin and myosin fibres bind together and form a gel hence making the muscles become stiff

16. Mechanism of Rigor Mortis Cessation of oxygen supply and metabolism After death, circulation and respiration stop. This halts oxygen delivery to tissues and prevents oxidative phosphorylation in mitochondria. The cells switch briefly to anaerobic glycolysis, producing lactic acid and lowering intracellular pH. Depletion of ATP ATP is essential for muscle contraction and relaxation. Under normal conditions: ATP binds to myosin heads and allows them to detach from actin filaments after contraction. ATP is also required to pump calcium ions back into the sarcoplasmic reticulum. After death, ATP production ceases, and existing ATP reserves are rapidly consumed.

17. Calcium ion accumulation With no ATP available, calcium pumps in the sarcoplasmic reticulum fail, leading to leakage of calcium into the sarcoplasm. This sustained rise in calcium keeps binding sites on actin exposed, allowing myosin heads to attach. Permanent actin–myosin cross-bridge formation Myosin heads bind to actin, but without ATP, they cannot detach. This results in a sustained contraction of muscle fibers and the stiffening characteristic of rigor mortis. Resolution of rigor mortis After 24–48 hours (variable with temperature and environment), autolysis and putrefaction cause proteolytic breakdown of muscle proteins, including actin and myosin, leading to loss of rigidity and eventual flaccidity

18. Rigor mortis Stiffening of muscle fibres . Physico -chemical process (ATP reduction). Involves voluntary and involuntary muscles. First appears in involuntary muscles – myocardium (1 hour). In voluntary muscles – sequence is proximodistal . Disappears in the same order in which it appeared. Testing of rigor mortis: Bending of joints.

19. Chronology of Rigor Mortis Onset after 2-3 hours of death Whole body stiff in about 12 hours Persists for another 12 hours Disappears in about 24 -48 hours Effects of Rigor Mortis Joints fixed markedly Goose skin Discharge of semen 20

20. Conditions affecting rigor mortis development Delayed by Cold Diminished musculature Accelerated by Activity Hyperthermia Drugs and poisons

21. Medico-Legal Importance of Rigor Mortis Estimation of time of death. Position of body at time of death (if body is already in rigor mortis and is moved from scene of death, it will remain so). Inappropriate rigor may indicate a body was moved several hours after death. 22

22. Conditions simulating Rigor Mortis Cadaveric spasm (instantaneous rigor) Cold stiffening Heat stiffening Embalming 23

23. Cold Stiffening (Freezing) Exposure to freezing temperatures, tissues become frozen and stiff due to solidification of body fats and fluids. Heat Stiffening (Heat rigidity) Coagulation of muscle proteins due to exposure to temperature above 65 °C Rigor mortis does not develop Body in pugilistic attitude Stiffening persist until decomposition sets in.

24. Cadaveric Spasms It is also known as  postmortem spasm, instantaneous rigor mortis, cataleptic rigidity, or instantaneous rigidity, is a rare form of muscular stiffening that occurs at the moment of death and persists into the period of rigor mortis The cause is unknown but is usually associated with violent deaths under extreme physical circumstances with intense  emotion 25

25. Cadaveric Spasm Only voluntary muscles are involved Can not be produced artificially Cadaveric spasm records last act of life and may be helpful in indicating manner of death (accident/suicide/homicide).

26. Cadaveric spasms

27. Late post mortem changes Decomposition Starts at cellular level soon after death, usually follows rigor mortis. Caused by a combination of autolysis and putrefaction Autolysis ( digestion of cells and tissues due to intrinsic enzymes and proteins) Putrefaction ( tissue breakdown as a result of bacterial action ) (In most environments, putrefaction dominates)

28. Autolysis Enzymes released from tissues cause auto digestion and disintegration of organs. Commences after 3-4 hours after death and continues steadily for about 2-3 days. Prevented by freezing

29. Bacterial Action (Putrefaction) Clostridium welchii and other organisms like staphylococci, B Proteus, release enzymes, which cause breakdown of various body tissues and gas formation. Lecithinase enzyme produced by C. Welchii dissolves cell membranes. C Welchii forms gas (H 2 S)

30. Decomposition results in liquefaction of the soft tissues over a period of time Decomposition is affected by temperature T he warmer the temperature , the earlier the decomposition process starts and the faster it progresses. The process is usually first visible 3-4 day as a green discoloration of the right iliac fossa

31. This ‘greening’ is the result of the extension of the commensal gut bacteria through the bowel wall and into the skin, where they decompose haemoglobin, resulting in the green colour . Bacteria travel through the blood vessels and spread throughout the body This results in linear branching patterns of variable discoloration of the skin that is called marbling

32. Over time, generalized skin discoloration occurs and blisters containing red or brown fluid form in many areas. When the blisters burst, the skin sloughs off G as formation in soft tissues and body cavities causes bloating of the face, abdomen, breasts and genitals The increased internal pressure causes the eyes and tongue to protrude and forces blood-stained fluid up from the lungs which often ‘leaks out’ of the mouth and nose as ‘purge fluid’

33. Time frame for changes in decomposition Greenish discoloration at the right iliac fossa ( 18-24 hours in summer). Discoloration spreads all over the body (24-28 hours). Greenish brown or purple red vein: marbling of veins (36-38 hours). Body emits foul, unpleasant odor due to gases formation (H 2 S, CO 2 , methane , etc.) Distension of abdomen – 18 -24 hours

34. Time frame for changes in decomposition Bloating of features (36-48 hours). Shifting of post-mortem staining Skin blisters (36-48 hours) and skin spillage , loose hair/nails (48-72 hours). Female genitalia pendulous (36-48 hours). Expulsion of fetus (48-72 hours).

35. Flies or maggots may also be seen in a decomposing body depending on the stage of development and the type of insect 24 h 4-5 days 10-20 days Eggs Maggots Pupae Adult flies Advanced ( over 4 to 5 days PM) Hot and dry climate : mummification due to tissue desiccation Cold and wet climates : adipocere formation due to conversion of free fatty acids into soaps by the action of Clostridium species Skeletonization : occurs over weeks to months

36. SLIPPAGE BLISTERING

37. SKELETONISATION MAGGOTS

38. BLOATING BLOATING BLOATING

39. SCAVENGERS AND MUMMIFICATION SCAVENGERS AND BLOATING

40. Factors Modifying Decomposition Process Accelerants Antemortem sepsis/infection Moisture/ hot environment /hyperthermia Clothing (heavy) or bedding Obesity Decelerants Refrigeration Cold environment Exposure to cool surfaces Air conditioning Hypothermia Embalming 41

41. Adipocere (Saponification) Due to hydrolysis and hydrogenation of body fats into substance, Adipocere, under influence of bacterial enzyme (lipase). Adipocere (yellowish, white greasy wax-like). Moisture/warm temperature – essential. Time required 3 weeks to 12 months (variable). 42

42. Adipocere (Saponification)

43. Mummification Dehydration/desiccation of tissues. Body becomes thin, brownish black and brittle. Hot dry climate and absence of moisture essential. Process takes about 1 – 2 months. 44

44. Mummification

45. Medico-Legal Importance of Adipocere/Mummification Ability to preserve the body, which can aid in personal identification and recognition of injuries. Time since death may be determined. Place of burial. 46

46. Maceration Death in -utero results in maceration (systemic autolysis ) rather than decomposition due to the sterile intra-uterine environment.. Bacterial putrefaction plays no role in the process. 3. The changes of maceration are only seen when a still-born fetus has been dead for several days before delivery. 47

47. Late post mortem changes Decomposition Adipocere formation Mumfication skeletonisation

48. END